It has been estimated that between 50 and 70 million people suffer from chronic back pain in the United States. In a significant number of cases, patients who are unaided by conservative therapies choose to undergo spinal surgery. The rate at which caregivers and patients opt for surgery also continues to grow as medical technology advances and surgical options increase. According to some estimates upwards of 750,000 or more spine surgeries are performed in the United States annually.
When necessary, spine surgery may provide great benefit to the patient, often allowing patients to resume activities previously abandoned because of the debilitating pain. Spine surgery, however, is not without risk. Operating on or near the spine means operating in close proximity to the sensitive vascular and neural structures that surround the spine. In particular, when accessing the spinal target site it is important to avoid inadvertently contacting or impinging on these sensitive tissues.
Traditionally, techniques for accessing the lumbar spine have utilized either of a posterior approach (to perform, among other procedures, posterior lumbar interbody fusion (PLIF)) and an anterior approach (to perform, among other procedures, anterior lumbar interbody fusion (ALIF)). Posterior-access is advantageous in that it typically involves traversing a relatively short distance through the patient and is unimpeded by major nerves or vessels. However, posterior-access generally provides limited exposure of the target site (e.g. intervertebral disc), oftentimes having to reduce or cut away part of the posterior bony structures (i.e. lamina, facets, spinous process) to achieve the limited exposure. Anterior-access to the lumbar spine on the other hand provides the advantage of accommodating a relatively large exposure. In order to access the spine from the anterior, however, the surgeon must traverse a greater distance through the patient's body tissue and the various internal organs and vessels located in front of the spine must be moved out of the way, a process that often requires an additional access surgeon.
More recently, techniques for accessing the lumbar spine through a lateral approach have been developed. For example, a minimally invasive retroperitoneal approach which traverses through the psoas muscle and employs neurophysiologic monitoring to detect and avoid nerves which run through the psoas muscle has become a valuable surgical option. The lateral approach may be advantageous in that it accommodates a large exposure akin to an anterior approach yet it may be gained through a smaller incision and without the need to retract the abdominal contents out of the surgical corridor. The lateral approach has proven to be quite successful in a number of ways (e.g. reducing pain, morbidity, recovery time, etc. . . . ). However, depending on patient anatomy, the lateral approach may be impracticable at the L5-S1 (and sometimes L4-L5) level because the iliac crest blocks the disc space. A need therefore still exists for a minimally invasive retroperitoneal approach to the L5-S1 (and sometimes L4-L5) disc space. Regardless of the approach, a need also exists for systems and methods that will allow the surgeon to better detect and avoid vascular tissue near the spine.